Rapid Method for Determining Fat Content in Meat by Using Continuous Wave Nuclear Magnetic Resonance (Cw-Nmr) Technique

Abstract

Development of rapid methods is often needed for the in-line process control of the proximate composition (e.g. fat or moisture content) of meat in the meat processing plants. This paper reports on the continuous wave nuclear magnetic resonance (CW-NMR) technique applied for determining fat content in fresh meat. The interfering moisture content in meat was removed by microwave drying and the dried residue was transferred quantitatively into the NMR-tubes. The total analysis time was about 35 min. Experiments were performed with pork (with a fat content from 1.7% to 21%), beef (with a fat content from 1.0% to 16.1%), lard (rendered pork fat) and tallow (rendered beef fat) samples and with their combinations: lard-tallow, lard-lean pork, tallow-lean beef and lard-tallow-lean beef-lean pork. The regression (prediction) equations (NMR-signal vs. fat content determined with the Soxhlet reference method) of pork and beef did not differ significantly. However, there was a noticeable difference between the regression lines of pure lard and pure tallow. Moreover, the latter ones differed from the regression equations of pork, beef and of the various meat-fat combinations. The variability of the fatty acid composition of the fat also seems to influence the stability of the calibration curves, because the sensitivity of the CW-NMR signal to the fatty acid composition interferes with the quantitative determination of fat content in meat.

Determination of fat content in meat by pulsed nuclear magnetic resonance (p-nmr) technique

“…It should be noted that, contrary to these results, the essential differences in the fatty acid composition of the fat and oil samples (SZEREDY & PERÉDI, 1956;BELITZ & GROSCH, 1985) induced a considerable difference in the CW-NMR signal (NAGY et al, 2000).…”

“…Comparing the regression equations between intensity of P-NMR signal and amount of pure fats and sunflower oil, it appears that, contrary to the results obtained with the CW-NMR technique (NAGY et al, 2000), the fatty acid composition has no substantial effect on them.…”

“…Rapid methods are often needed for the in-line process control of the fat content of meat in meat processing plants. A previous report (NAGY et al, 2000) demonstrated that, among others, the high sensitivity of continuous wave nuclear magnetic resonance (CW-NMR) signal to the fatty acid composition interferes with the quantitative determination of fat content in meat, inducing occasionally a noticeable bias in the prediction. NILSSON and KOLAR (1970), as well as CASEY and MILES (1974) obtained an acceptable accuracy by determining the fat content in meat with the NMR technique.…”